Conventionally, a system that generates a display image by processing an omni-directional image (fish-eye image) captured by a camera having a fish-eye lens has been proposed (for example, refer to Patent Literature 1 to Patent Literature 3). As one of such image processing systems, a system is known in which a display image of an imaging object moving in an imaging area is generated by using an clipped image clipped from an image (imaging area image) in which the imaging area is captured from above.
In the conventional system like this, since the imaging area image is captured by the camera having the fish-eye lens, the imaging object inclines according to the position of the imaging object in the imaging area image. Thus, processing for rotating the clipped image according to the inclination is performed when the display image is generated from the clipped image clipped from the imaging area image.
However, in the conventional system, when the imaging object passes nearly just under the camera, the orientation of the imaging object displayed in the display image suddenly changes due to the influence of the processing for rotating the clipped image, resulting in that the display image is hard to see.